It is frequently necessary to form an even layer of comminuted material such as fibers, chips, and the like on a substrate in the production of plate-like building material. See for instance my U.S. Pat. No. 3,864,066 issued 4 Feb. 1975. It is necessary that such an arrangement form on the substrate a layer of uniform thickness and homogeneity. In order to maximize production speeds it is also necessary that the substrate move as fast as possible. To this end the spreading arrangement must be able to handle a relatively large amount of material, while at the same time there should be no decrease in uniformity of the layer put down on the substrate.
In a known system a bin, hopper, or the like loaded with a supply of comminuted material is provided adjacent the substrate. Extending upwardly out of this supply is a first conveyor band which displaces the material upwardly downstream and drops this material into the top of a conveyor chute. A distributing arrangement, such as a brush, is provided at the bottom of the chute for spreading the material dropped thereinto on the substrate. Such a device has the considerable disadvantage that the amount of material it can evenly spread is severely limited. The displacement rate of the lifting belt as well as the rotation rate of the spreading brush can only be increased to a certain point beyond which the results are so uneven as to be unusable.